Week 5 Blog Entry

This week in AP Chem, we focused in on VSEPR models and how they can tell us about the shape of a molecule. We first created balloon models of given molecules, as they give a pretty good representation on how a molecule will be shaped. In our table groups, we drew the Lewis structure for our molecule and then counted the bonding atoms and the lone pairs, which also gave us our molecular class. After we used this information to create our balloon models, we observed how the shape the balloons formed with each other made a certain shape for the electron domain geometry (tetrahedral, trigonal bipyramidal, etc.).

We also made gumdrop models of the same molecule, but this time created the molecular domain geometry instead of the electron domain geometry. If there were any lone pairs about the central atom, then the molecular and electron domain geometries would differ.

We briefly discussed the percent copper in brass solution lab we performed last week and created a graph with the absorbances of our solution. We used this graph to calculate our mass percent of copper.

We also completed a lecture quiz on Polarity and reviewed Lewis structures near the end of the week. We completed a POGIL on hypervalency, and noticed which atoms could be hypervalent (atoms in period three and above.).

I am beginning to notice my improvement and efficiency in drawing the Lewis structures for many different molecules, although some of the more challenging molecules still manage to get the better of me. Admittedly, I am still kind of shaky with the entire resonance structure and bond order concept, although I am beginning to see the correlation between the two concepts. I feel like I also need some more practice in VSEPR models. I haven’t fully memorized the electron and molecular domain geometries yet, but I now understand why certain angles in the electron domain are formed.

When we created balloon models, we represented the bonded atoms as red balloons and the unbounded electrons as white balloons. Because these white balloons were slightly bigger than the bonded atoms, they wanted to push down on the bonded atoms in order to decrease the repulsion between the electrons.  This helped me understand the concept of the VSPER theory—how atoms want to arrange themselves in the best way to minimize repulsion.

Overall, I think I have dealt with a great deal of new material this week. I have become more confident in drawing Lewis structures, even though I still feel I have a long way to go until I become completely adept in drawing them perfectly. I still have trouble with drawing resonance structures and making sure I have compensated for every electron that belongs in that molecule. I also have some room for improvement in VSEPR models, mostly in memorizing the angles that form from the central atom and exactly what shape they create. Hybridization and polarity were also somewhat challenging concepts for me, which means that I’ll devote extra attention to them to ensure that I understand them fully.